The present invention relates to an anchor for a screw or similar fastener, and more particularly, to an anchor for permitting the secure threading of a screw into an over-sized or worn hole.
A persistent problem encountered when replacing mounted hardware is the screw holes within the material become stripped or damaged. For example, when installing door hinges or replacing the strike plate or latch plate, the threads of the wood holes may be worn and enlarged, such that the screw remains loose despite tightening. One repair method includes using a larger screw to match or exceed the hole diameter. However, the larger screw head may protrude from the mounting hole of the hinge or plate. Another method includes inserting and gluing small splints (commonly toothpicks) into the hole to reduce the diameter, often resulting in an uncertain and temporary repair. Yet another repair method involves enlarging the diameter of the hole, driving a glued dowel into the hole, and creating a new screw hole in the dowel. Although effective, this method requires excessive time and labor. A further method of repair may include fastening the hinge to the jamb by driving a long screw (such as a 3 inch drywall screw) through the worn hole and into the jack stud therebehind. The diameter of the long screw head may be too small to provide adequate holding force; and the screw head likely will have a finish that does not match the hinge. Furthermore, there is commonly a shim gap between the hinge jamb and the jack stud, where the long screw may draw the hinge jamb towards the jack stud, closing the shim gap and warping the hinge jamb.
Common plastic expansion-type screw anchors may also be used. However, there are at least three issues with these anchors. First, once inserted, the anchors protrude from the surface of the wood, preventing the proper mounting of the hinge plate against the surface of the wood, so that the hinge plate lies flush within the mortise. Second, many anchors tend to twist as the screw is threaded into the anchor. Finally, the anchors may unintentionally withdraw from the hole when the screws are removed at a future point in time.
What is needed is an anchor that will mount flush or below the surface of the material surrounding the hole to permit proper mounting of the hardware. The anchor should prevent twisting when the screw is torqued. The anchor should be designed to remain within the hole until the user manually removes the anchor. Furthermore, the anchor should be capable of being easily driven into the hole without excessive damage to the material. Moreover, the anchor should facilitate the use of the original screw when possible, to maintain matching hardware, finish, and the like.